Heretofore it has been known to neck in tubular bodies such as can ends and then outwardly flange the end of the body so as to receive a can end thereon of smaller diameter than a body wall which has not been necked-in. A major problem has existed in the known prior art techniques, namely, wrinkling of the neck of the container. Thus, existing can body manufacturing typically requires a thickened neck structure for the can so that it will not wrinkle in forming the end. Previous minimum wall thickness in the region of the can to be necked-in was about 0.007-0.0075 inches. With the present invention and method of forming, a uniform thickness for the region to be necked-in and the remainder of the body wall of the container of 0.005 inches is possible without wrinkling.
Another problem of the prior art which was inherent because of the first problem was how to obtain a plurality of closely-spaced successively necked-in portions for a container body wall on an economical basis. With the increased thicknesses required in the prior art techniques at the location of the necked-in area, the costs were prohibitive and/or the wrinkling excessive.